Foundation pile having a spiral ridge and method of underpinning using same

ABSTRACT

A foundation pile or pile segment is described that provides support for a structure such as a building foundation. The pile includes a generally solid body having a top end wall, a bottom end wall adapted for providing end load bearing capacity, and all around sidewalls. The sidewalls extend between the top end wall and the bottom end wall and has at least a pair of oppositely disposed spiral ridges that extend generally about the surface of the sidewalls. Further, each spiral ridge extends in a generally spiral direction from the top end wall to the bottom end wall. The spiral ridges provide an offset surface that extends generally outward from the surface of the sidewalls. The offset surfaces provide additional load bearing capacity to the foundation pile.

BACKGROUND OF THE INVENTION

The present invention relates generally to an apparatus and method forsupporting above-ground structures and/or repairing structuralfoundations. More particularly, the invention relates to an apparatusand system that includes a foundation pile segment, or a plurality ofcorresponding foundation pile segments, having enhanced supporting orunderpinning capacity. The invention further relates to a method ofsupport installation or underpinning utilizing such a pile or piles,whereby the pile is driven vertically into the earth.

Foundation pile segments, or simply, foundation piles, are driven intoand installed in the earth to transfer thereto, the loads applied to orresulting from above-ground structures such as buildings, slabs, wallsand columns. An installed foundation pile obtains its load bearingcapacity primarily from two surface areas: the bottom surface and thesidewall surfaces. The bottom surface provides the primary, direct endload bearing capacity. The sidewall surfaces, on the other hand,frictionally engages the adjacent soil to provide frictional surfaceareas that resist the downwardly directed load.

BRIEF SUMMARY OF THE INVENTION

A foundation pile apparatus according to the present invention isutilized to support an above-ground structure such as buildings, walls,slabs, and columns. The inventive foundation pile includes a generallysolid body (e.g., rounded, square or rectangular shaped, cylindrical,etc.) having a top end wall, a bottom end wall and all around sidewallsextending therebetween. In several embodiments, the body of the pileapparatus is precast concrete and further, has a generally rounded shape(i.e., a generally circular cross section). The sidewalls extend betweenthe top end wall and the bottom end wall and has at least one (but,preferably two or more) spiral ridge that extends generally about, thesurface of the sidewall. Further, this spiral ridge extends in agenerally spiral direction from the top end wall to the bottom end wall.The spiral ridge provides an offset surface that extends generallyoutward from the surface of the sidewalls. The surface area of thisoffset surface significantly enhances the load bearing capacity of thepile.

For purposes of the present Description, the term “spiral” or “spirally”is used to refer to a direction in which the ridge traverses bothcircumferentially and downwardly about the sidewalls of the pile body.In various embodiments of the invention, the spiral ridge may traverseup to or less than one-quarter of the circumference, and even the fullcircumference or beyond. The spiral ridge may also traverse the fullheight of the pile body, a distance less than the full height, and/or adistance less than the full height and in between the end walls

In another aspect of the present invention, a method of installingfoundation piles for supporting an above-ground structure is provided.The inventive method includes the step of providing a foundation pileapparatus such as that described above. The foundation pile apparatus isdriven into unexcavated earth a desired distance and set a desireddepth, whereby said offset surface and said end wall support a load onsaid pile apparatus. Preferably, a downward force is applied upon thefoundation pile (e.g., upon a top end wall), whereby the pile apparatusmoves downwardly and rotatably into the unexcavated earth. In thisdriving step, the pile may rotate about ¼ turn for every given downwarddistance into the earth (wherein the given downward distance correspondsto about the height of the pile). Moreover, in rotating the pile, thespiral ridge preferably loosens the soils adjacent the pile as the pileis driven downwardly into the earth, thereby facilitating and makingmore efficient the driving step.

These and other objects, features and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed descriptions and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of a foundation pile according to thepresent invention;

FIG. 1A is a perspective view of the foundation pile of FIG. 1

FIG. 2 is a bottom view of the pile apparatus of FIG. 1;

FIG. 3 is a top view of the pile apparatus of FIG. 1; and

FIG. 4 is the elevation view of FIG. 1 modified as a simplifiedforce-body diagram in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Each of FIGS. 1-4 illustrates a foundation pile (and method ofinstalling same) embodying various aspects of the present invention.These particular foundation piles are illustrated and described hereinfor exemplary purposes. Variations of the foundation pile and methods ofutilizing or installing the same, according to the invention, willbecome readily apparent to one skilled in the relevant structural ormechanical art upon reading the present Description and/or viewing theaccompanying Drawings. Thus, the present invention should not be limitedto the structures, systems, and methods described below.

Referring to FIG. 1, a foundation pile according to the presentinvention is depicted in the form of a precast concrete pile 101. Theconcrete pile 101 may be made from materials, mixtures, and componentsgenerally known in the art. The concrete pile 101 has a top end wall105, a bottom end wall 107, and an all-around sidewall(s) 113 extendingtherebetween. The top end wall 105 is designed to sustain a downwardlydirected driving force (e.g., applied by hydraulic ram) duringinstallation of the pile 101 into the soil or earth. The bottom end wall107 is provided sufficient bottom surface area to meet certain end loadbearing requirements of the pile 101 (also the cross-sectional area ofthe body must be sufficient for buckling and torsional loads). In theembodiment of FIG. 1, the top end wall 105 and the bottom end wall 107are generally identical, in that each has a flat surface of generallythe same surface area. In further embodiments, the sidewalls 113 may notbe generally straight and the bottom end wall 107 may provide a largerand/or irregular surface area.

The foundation pile 101 of FIG. 1 also has an elongated bore or hole 111that extends between the end walls 105, 107. The hole 111 accommodates ahigh strength strand for the foundation pile 101 that is used in asystem of corresponding segmental piles. Such a system and correspondingmethod of installation are described and illustrated in U.S. Pat. No.5,288,175 (which has been assigned to the assignee of the presentinvention)(hereby incorporated by reference for all purposes and made apart of the present disclosure). The inventive foundation pile isparticularly applicable for use in such a system and installationbecause, as will be further discussed below, the enhanced attributes ofa single inventive foundation pile may be realized multi-fold in amulti-pile system.

In other embodiments of the invention, the foundation pile may beconstructed of materials such as wood, metal, epoxy, or other materialsgenerally known and used for foundation pile construction. In furtherembodiments, the foundation pile may take on other shapes including agenerally square or rectangular configuration or a generally tapered orbell-shaped form. The shape of the concrete pile 101 in FIGS. 1-3 may,for purposes of the present invention, may be referred to as rounded orcylindrical.

In one unique aspect of the invention, the preferred concrete pile 101is precast in a special-shaped mold. As illustrated by FIGS. 1-3, such amold provides the inventive concrete pile 101 a pair of spiral ridges109, each of which is directed or extends spirally downward about thesidewalls 113 of the concrete body 103. The spiral ridge 109 preferablyextends entirely from the top end wall 105 downwardly to the bottom endwall 107. As best shown in FIG. 2, all spiral ridge “according to theinvention” is defined, at least partially, by a notch or offset 109 afrom the sidewalls 113 that creates an offset surface 1036 extendingtherefrom and which, as will be explained below, enhances the supportcapacity of the foundation pile 101. The pile 101 is preferablyoriented, during installation, such that both offset surfaces 109 bfaces generally downward (rather than generally upward) or in thedirection of rotation (denoted by “AA” in FIGS. 1 and 3).

With reference to FIGS. 2 and 3, the mold is shaped and sized such thatthe ridge 109 provides two complementary semi-circles of the concretebody 103. The complementary semi-circles 113 a and 113 b are offset bythe width or depth of each notch 109 a. As mentioned previously, theconcrete pile 101 is preferably a precast molded body. To facilitateremoval of the concrete body 103 from the mold, the concrete body 103may be provided with a slight taper or curvature. In many applications,the molds, and thus the concrete piles 101, are typically 11 to 12inches in height and about 6 inches in diameter. With these dimensions,a concrete pile having two spiral ridges is formed wherein the spiralridges extend downwardly at about a 45° angle and horizontally traversesapproximately 90° or one-fourth of the sidewall's circumference.

Because of the 45° angle of the spiral ridge 109, the round shaped pile101 may be driven vertically downward into the unexcavated earth in amanner that produces a quarter turn (or 90° turn) with each distanceequaling the height of the pile. In this way, a concrete pile 101 havinga height of 12″ and a diameter of 6″ rotates about ¼ turn or 90° or forevery 11-12″ penetration into the soil. Moreover, the spiral ridge 109provides a facilitating function during installation of the pile 101.Specifically, as the pile 101 is impacted by a generally verticaldownward force (i.e., from a hammer or hydraulic ram) on the top endwall 105, the spiral ridge 109 causes the soil immediately in front ofthe offset surface 111, and adjacent the sidewall 113 and bottom endwall 107, to loosen. In this way, the resistance of the soil to downwardmovement of the pile 101 into the earth is reduced. It has been observedby the Applicant that a concrete pile 101, such as the embodimentdepicted in FIGS. 1-3, may be driven or moved deeper into the earth thana traditionally shaped and sized pile (i.e., without the spiral ridge101). Tests were conducted to measure the relative soil or groundpenetration obtained by the inventive pile (as shown in FIGS. 1-3) andthe traditional prior art pile when the same downward force is appliedto both and in similar solid conditions. These tests showed that theinventive pile is driven a depth that is about 18% deeper than the depthto which the prior art pile is driven.

In addition to the benefit of driving a pile deeper and faster into theearth, the inventive pile also allows for more segmental piles to beinstalled in one location. Accordingly, a system of such piles provideseven greater support to the above-ground structure.

It will be apparent to one skilled in the art that other dimensions ofthe pile apparatus, of concrete or other material, may be obtained asrequired. For example, concrete piles may be made shorter and smallerthan the 12″ high and 6″ diameter piles depicted in the Figures. It willalso be apparent to those skilled in the art that there may be certainpractical limitations, i.e., strength, to the size and dimensions of thepile design.

Now also referring to FIG. 4, the foundation pile 101 according to theinvention is provided with structural features that enhance thesupporting capacity of the pile (as well as facilitate itsinstallation). In particular, the inventive foundation pile 101 isequipped with the structurally advantageous spiral ridge 109. The spiralridge 109 provides an additional load bearing surface in the form of theoffset surfaces 109 b. The offset surfaces 109 b supplement the bearingcapacity of the end wall 107 to increase the overall load bearingcapacity of the foundation pile 101 (which is also supplemented by thefrictional surface areas provided by the sidewalls). This is illustratedby the simplified force-body diagram of FIG. 5, wherein the resistantforce or load bearing capacity of these surfaces is denoted by “BB”, thefrictional forces denoted by “CC”, and the vertical load imparted on thepile 101 is denoted by LL. With respect to the foundation pile 101 ofFIGS. 1-3, a spiral ridge that is 12″ long and ½″ wide provides anadditional load bearing surface of 6 square inches, or a total of 12square inches for two spiral ridges. In contrast, if the foundation pileof FIGS. 1-3 did not have the spiral ridges (as in the prior art), itsend load bearing surface would be provided by the end wall surface areaor approximately 28 square inches (e.g., πR², where R=3″). Thus, afoundation pile according to the invention provides 1.5 times more loadbearing capacity than the end wall of a corresponding prior artfoundation pile—as a result of the spiral ridge.

A system of corresponding or segmental piles further illustrates theadvantage provided by the inventive foundation pile. In such systems andinstallations, it is not uncommon to drive fifteen foundation piles intothe earth. Thus, in accordance with the inventive method, fifteen pilesmay be driven to provide an additional end bearing surface capacity of180 square inches (12 square inches×15 piles). As a result, in a methodaccording to the invention, the series of piles may be driven deeperinto the earth and provide greater end bearing capabilities. Moreover,with the greater depth, greater stability may be achieved because theconcrete piles or at least more of the concrete piles may be driven intonon-weather affected zones of the earth. Still further, with pilesdriven into the earth, the system of piles provides greater frictionalsurface wear (because of the additional piles). These are just some ofthe important advantages and benefits afforded to one employing themethod according to the invention and the pile apparatus according tothe invention.

The systems, apparatus, and methods described herein are particularlyadapted for installation of a pile segment in a system of piles, e.g.,segmental piles, and preferably, concrete or wooden piles. However, itwould be apparent to one skilled in the relevant mechanical orstructural art upon reading the Description and viewing the accompanyingDrawings, that the various aspects of the invention are also applicableto other structural or foundation support systems. For example, thefoundation pile and method of installing same, may be adapted for singlepile installations or multiple installation (e.g., segmental piles).Moreover, the foundation pile segment may be constructed of materialsother than concrete or wood, may take on other shapes such as square,rectangular, or bell-shaped. Further yet, the piles may have more thantwo spiral ridges or a single spiral ridge that traverses the entirecircumference of side wall one or more times.

Thus, the foregoing description is presented for purposes ofillustration and description, and is not intended to limit the inventionto the forms disclosed herein. Consequently, variations andmodifications commensurate with the above teachings and the teaching ofthe relevant art are within the spirit of the invention. Such variationswill readily suggest themselves to those skilled in the relevantstructural or mechanical art. Further, the embodiments described arealso intended to explain the best mode for practicing the invention, andto enable others skilled in the art to utilize the invention and such orother embodiments and with various modifications required by theparticular applications or uses of the invention. It is intended in theappended claims be construed to include alternative embodiments to theextent that is permitted by prior art.

1. A foundation pile apparatus for providing support to an above-groundstructure, said foundation pile comprising: a generally solid bodyhaving, a top end wall, a bottom end wall adapted for providing loadbearing capacity, and all around sidewalls extending between said topend wall and said bottom end wall, said sidewalls having a ridgeextending generally about said sidewall and in a generally downwarddirection from said top end wall to said bottom end wall, wherein saidridge has an offset surface extending generally outward from a surfaceof said sidewalls, said offset surface providing additional load bearingcapacity.
 2. The apparatus of claim 1, wherein said ridge is a spiralridge extending in a generally downward spiral direction about saidsidewalls.
 3. The apparatus of claim 1, wherein said sidewalls include asecond spiral edge extending generally about said sidewalls.
 4. Theapparatus of claim 3, wherein said body is a precast concrete bodyformed to include two vertical section halves, said section halvesmutually facing one another to create an offset surface that forms saidspiral ridges.
 5. The apparatus of claim 1, wherein said sidewallgenerally tapers radially outward from said top end wall to said bottomend wall.
 6. The apparatus of claim 1, wherein said ridge extendsspirally downward about said sidewall from said top end wall to saidbottom end wall.
 7. The apparatus of claim 1, wherein said body includestwo spiral ridges, each said ridge extending spirally downward aboutsaid sidewall and traversing horizontally about said sidewall an arcdistance of about 90°.
 8. The apparatus of claim 1, wherein said bodyincludes two spiral ridges, each with offset surfaces, said offsetsurfaces providing a load bearing surface that is between about 0.35 to0.55 times the load bearing surface of said end wall.
 9. The apparatusof claim 1, wherein said body has a generally round shape.
 10. A methodof installing foundation piles for supporting an above-ground structure,said method comprising the steps of: providing a foundation pileapparatus having, a top end wall, a bottom end wall adapted forproviding end bearing capacity, and all around sidewalls extendingbetween said top end wall and said bottom end wall, said sidewallshaving a spiral ridge extending generally about said sidewall and in aspiral direction extending from said top end wall to said bottom endwall, wherein said spiral ridge has an offset surface providingadditional load bearing capacity; and driving the foundation pileapparatus into unexcavated earth a desired distance, including settingthe apparatus to a desired depth, whereby said offset surface and saidend wall support a load on said pile apparatus.
 11. The method of claim10, wherein said driving step includes applying a downward force uponsaid foundation pile, whereby said pile apparatus moves downwardly androtatably into the unexcavated earth.
 12. The method of claim 11,wherein said driving step includes driving the foundation pile such thatthe pile rotates about ¼ turn for every given downward distance into theearth, said given downward distance corresponding to about the height ofthe pile.
 13. The method of claim 11, wherein said step of applying adownward force rotates the pile such that the spiral ridge loosens thesoils adjacent the pile as the pile is driven downwardly into the earth.14. The method of claim 13, wherein said step of providing a pileapparatus includes providing a second spiral ridge about said walls, andwherein said offset surface generally faces the direction of rotation ofthe pile apparatus during the driving step.
 15. A method of installingfoundation piles for supporting an above-ground structure, said methodcomprising the steps of: providing a concrete pile apparatus having atop end wall, a bottom end wall adapted for providing end bearingcapacity, and all around side walls extending between said top end walland said bottom end wall, said side walls having at least a pair ofspiral ridges thereon that extends generally about a surface of saidside wall and in a spiral direction extending from said top end wall tosaid bottom end wall, wherein each said spiral ridge has an offsetsurface extending generally outward from said surface of said sidewalls,said offset surface providing additional load bearing capacity to saidconcrete pile apparatus; and applying a downward force to said concretepile apparatus to drive the concrete pile apparatus into unexcavatedearth a desired distance from the structure, including setting theapparatus to a desired depth whereby said spiral ridge providesadditional load bearing capacity, and whereby said spiral ridge engagesthe unexcavated earth to cause said concrete pile apparatus to rotate asthe concrete pile apparatus moves downwardly into the unexcavated earth.16. The method of claim 15, wherein said step of applying a downwardforce causes the foundation pile to rotate about ¼ turn for every givendownward distance, said given downward distance corresponding to aboutthe height of the pile.
 17. The method of claim 15, further comprisingthe step of installing one or more concrete pile apparatuses atop thefirst concrete pile apparatus by repeating, with respect to one or moreadditional concrete pile apparatus, said steps of providing a concretepile apparatus and applying a downward force thereto, whereby the totalload bearing capacity of a pile system including the installed pileapparatuses includes load bearing capacity provided by offset surfaceareas of spiral ridges on each installed concrete pile apparatus.
 18. Afoundation pile apparatus for providing support to an above-groundstructure, said foundation pile comprising: a concrete body having a topend wall, a bottom end wall adapted for providing load bearing capacity,and all around sidewalls extending between said top end wall and saidbottom end wall, said sidewalls having two spiral ridges extendinggenerally about said sidewall and in a generally downward spiraldirection from said top end wall to said bottom end wall, wherein eachsaid spiral ridge has an offset surface extending generally outward froma surface of said sidewalls, said offset surface providing additionalload bearing capacity.
 19. The apparatus of claim 18, wherein saidconcrete body is a precast concrete body formed to include two verticalsection halves, said section halves mutually facing one another tocreate said offset surfaces that form said spiral ridges.
 20. Theapparatus of claim 19, wherein each said spiral ridge extends spirallydownward about said sidewall and traverses horizontally about saidsidewall an arc distance of about 90°, and wherein each said offsetsurfaces together has a load bearing surface of between about 0.33 timesor greater than the load bearing surface of said end wall.
 21. Thefoundation pile of claim 20, wherein said concrete body has a generallyround shape.